()方法常用于复杂、没有事故经验的新开发系统。A.直观经验分析 B.系统安全分析 C

生活中各种物质都是由元素形成的，请你用C、H、O、N、Cl、Ca六种元素中的一种或几种组成相应物质，按要求填写化学式：

①农村的清洁能源“沼气”是______；

②充入食品包装袋中可防腐的气体单质是______；

③在农业上常用来改良酸性土壤的一种碱是______．

在界、门、纲、目、科、属、种的七个等级中，你认为哪个等级生物的共同特征最多？哪个最少？说出你的理由．

亚洲第一长河是[ ]

A．闽江

B．尼罗河  

C．密西西比河  

D．长江

男性，65岁，高血压，病人睡眠中突感极度胸闷，气急咳嗽痰中带血，端坐呼吸。

估计该病人发生了

A．高血压性心脏病

B．高血压危象

C．高血压脑病

D．急性肺水肿

E．肺梗死

阅读理解。

     Women have jumped ahead of men for the first time in using the Internet to do their holiday shopping,

according to a study published last week in the US.

     For Years men have been more likely to shop on the Internet than women, but during the 2011 holiday season 58 percent of those making online purchases (购买) were women.

     "It shows how mainstream the Internet is becoming", said Lee Rainie, director of the Pew Internet and American Life Project group, which carried out the study.

     Rainie said it was only a matter of time before women shoppers caught up with men. This is because

women traditionally make decisions about spending.

     Users were more likely to shop online to save time. Internet users between the ages of 18 and 29 were responsible for some of the most dramatic increases in the online gift-buying population this time around.

     However, three-quarters of the US Internet users did not buy holiday gifts online in 2011. They worried about credit card security(安全), or just compared online prices with off-line prices, then dashed off to the shops to get the best deals.

     "But even if shoppers don't buy online, websites are becoming promotion tools for stores," said Dan Hess, vice president of Comscore Networks Inc. Hess said that actually most stores' websites can make customers fully believe the security of their credit card numbers. And most are able to ensure that gifts arrive

on time. "It's all about making the shopping experience more efficient, more reliable and more

comfortable." Hess said.

1. Which of the following statements is true?

A. More women shopped online than men in 2011.

B. There were fewer women online shoppers than men in 2011．

C. Most of the Internet users between the ages of 18 and 29 are women.

D. People in the US were more likely to buy gifts online.

2. From the passage we can infer that________.

A. men usually decide how to spend money in the family  

B. women usually decide what to buy in the family

C. the Internet is used in all the shops.                

D. more and more shops will sell their goods online.

3. According to Dan Hess, shopping online is _______.

A. unsafe

B. convenient

C. a waste of time

D. cheaper

4. What can we know from the passage?

A. American people only buy gifts in holidays.  

B. Shopping online is fun for women.

C. Shopping off-line provides better service.  

D. Young people like to do gift-shopping online.